Holding means for projectile fins



Dec. 8, 1953 E. c. M. DAssls FONSECA 2,661,589

HOLDING MEANS FOR PROJECTILE FINS Filed Feb. 16, 1949 s Sheets-Sheet 1 Dec. 8, 1953 Filed Feb. 16, 1949 E. C. M. D'ASSIS FONSECA HOLDING MEANS FOR PROJECTILE FINS 3 Sheets-Sheet 2 Dec. 8, 1953 Filed Feb.

E. C. M. D'ASSIS FONSECA HOLDING MEANS FOR PROJECTILE FINS 3 Sheets-Sheet 3 Patented Dec. 8, 1 953 HOLDING MEANS FOR. PROJECTILE FINS Evelyn Cecil Muschamp dAssis Fonseca, Bristol, England, assignor to The Bristol Aeroplane Company Limited, Bristol, England, a British ompany Application February 16, 1949, Serial No. 76,812

Claims priority, application Great Britain May 10, 1948 3 Claims.

This invention concerns fins for projectiles, more particularly for use with sea mines launched from aeroplanes.

An object of this invention is to provide an improved construction of stabilising fin which is capable of being folded against the projectile so that the room taken up in stowing the projectile is substantially reduced.

Another object is to provide for automatic unfolding of the fins when the projectile is launched.

Yet a further object of the present invention is to provide a construction of fin which may be readily folded and which, when unfolded, is simply and effectively supported against deflection by the aerodynamic forces acting on it.

According to the present invention the fins of a projectile are carried by a frame, adjustably attached to the projectile, for pivotal movement and are urged from a folded position against the projectile to a position radially of the projectile and the fins are adapted initially to be held, each independently, in folded position to the frame by a catch, all said catches being simultaneously unfastened from the frame and connected with a common release gear by adjustment of the frame on the projectile.

With this arrangement each fin may be folded and held in position by its catch and this operation may be done by one person. When all the catches are engaged the release gear may be connected to them and the catches then released in a simple manner without great effort. It will be seen, therefore, that the operation of folding the fins, and connecting them to the release gear, does not call for several persons acting on the fins at the same time.

According to another feature of this invention each fin is spring-urged to its unfolded position the spring acting on the fin through a link, one member of which is carried around with the fin when the latter is unfolded so that one of its ends enters, and is held in, a slot of the frame in such a position that areodynamic forces on the fin are applied by said member to the sides of the slot and are not transmitted to the spring. Each fill-holding catch preferably comprises a pin having a pair of spaced heads, the shank of the pin being adapted to enter an open-ended slot in the frame and fin so that the spring pull on the fin is taken by the heads. The release gear preferably comprises, for each catch, a rod secured to that head of the pin which engages the frame and a common anchorage for all said rods the arrangement being that when the frame is axially adjusted, as indicated, the pin disengages the frame.

A practical application of the present invention will now be described by way of example only, with reference to the accompanying drawings whereof:

Figure 1 is a side elevation of a sea mine in accordance with the present invention,

Figure 2 is a view in the direction of the arrow 2 of Figure 1 and to an enlarged scale,

Figure 3 is a view in the direction of the arrow 3 of Figure 2 showing the fins and fin-attachment means of the sea mine in Figure 1 to an enlarged scale and partlyv in section,

Figure 4 is a similar view to Figure 2 and showing certain parts of the fins and attachment means in section, and

Figure 5 is a scrap view showing a detail of construction of the attachment means.

Referring to Figures 1 and 2 of the accompanying drawings: the sea mine is generally indicated by the reference numeral I 6 and comprises a mine H and a fin system [2 and attach-. ment means therefor. The fin system is removably attached to the mine I I and comprises four fins [3 which are hinged at it (Figure 2) toa frame [5, the fins being capable of being folded against the frame or of being swung outwardly so as to lie radially of the mine. The frame I5 is attached to the mine H by a device which permits the fin system to be automatically thrown off on impact of the mine with the sea.

Referring now to Figures 2, 3 and 4: it will be observed that the frame l5 comprises a cylindrical member l6 having a pair of axially spaced flanges I1 of square outline (Figure 2). A fin I3 is pivoted at each corner of the flanges H, the fins being preferably mounted on tubes l8 (Figure 3) which extend from one flange to the other. The frame [5 is placed over one end of the mine II which enters the cylindrical part it of the frame.

Each fin I3 normally lies along one edge of the square frame I! as is clear from Figures 2 and 4. The mine is stowed in the aircraft with the fins folded so that the amount of room taken up is as small as possible When the mine is launched the fins are'automatically unfolded and assume their radial position-see the chain dotted position of the fin l3 in Figure e.

To hold the fins in the folded position there is provided for each fin a catch! comprising a pin [9 having spaced heads 20, 2| (Figure 5). Each fin is formed with an upstanding flange 22 and there is formed in the fiangeanopen-endedslot 23. The upper end of the cylindrical part I6 of the frame I5, at a point opposite the slot 23, is also formed with an open-ended slot 24. It is arranged that when a fin is folded against the frame I= the open-ended slots 23, 24 arebrought opposite each other and the shank of the pins I9 enters the slots so that the heads 26, 2| of the pin engage the cylindrical part I6 and the flange 22 respectively. Each I 3 is spring urged to assume its unfolded position and the pin I9 applies the pull of the spring to the cylindrical part I6 and the fin is therefore held folded.-

Each pin I9 is connected by a rod to a common anchorage 26 disposed towards the centre of the frame I5. The anchorage comprises a bracket 21 through which there passes a hook 28. The shank of the hook is threaded through an opening in each of the rods 25. The hook 28 is connected by a cable to the aircraft when the mine is stowed.

. The bracket 21 projects to within the cylindrical part I6 of the frame I5 as shown in Figure 3 and it is arranged that when the frame is placed position on the mine II the end of the mine engages the bracket 21 and displaces it axially by an amount such that the heads 26 of the pins I9 are raised clear of the part I6 i. e. the pins I9 are moved out of the slots 24. The spring pull on each fin will then be transmitted through the pin I9 and the rod 25 to the common anchorage 26.

In this way after the frame I5 has been applied to the mine I I the fins I3 are held in their folded position by the rods 25 and anchorage 26.

With the arrangement described, each fin I3 may be individually moved to its folded position and is associated catch pin I9 placed in position so that the fin is held to the frame I5. When the four fins are thus held in their folded position each catch is connected by the rod- 25 to the common anchorage 26. The frame is then slid over one end of the mine II and in so doing the bracket 21 is axially displaced simultaneously to release the four catch pins from the part I6 of frame I5. The tendency of the fins to unfold is then resisted by the rods 25 and anchorage 26 which constitute with the pins I9 a release gear for the fins.

When the mine is launched the cable removes hook 26 and thus releases the rods 25 and the fins I3 fly outwardly, the rods 25 and pins I9 being thrown clear by this action. The pins I9 will readily disengage the fins I3 since they are only held in the open ended slots 23. The fins I3 will be pulled outwardly to their radial position by the spring means referred to above.

Each fin I3 carries aii'ar'm 29 (Figure 4) which is' pivotally connected to a link 30 at 3|. The free end 39 of the link 36 engages the surface 32 of a slide 33 which is secured to the part |6 of frame I5. The free end 39 of the link 30 is adapted to slide along the surface 32 and into slot 34 between the slide 33 and a finger 36. A spring 36 is anchored at 31 to the link 36 and at 38 to a bracket carried by the part I6. The spring 36 is the spring referred to above which is pro vided to move the fin I3 from the folded to the unfolded position.

When the fin I3 is in its folded position the arm 29 and link 30 are in line and lie generally along one side of the edge of the flange I1 (see the full line position Figure 4). When the fin is released in the manner described above the spring 36 rotates the fin I3 and the arm 29 and link 30 are carried around with the The arrange ment is that as the fin swings outwardly the free end of the link 36 is drawn along the surface 32 to within the slot 34. When in the unfolded position (shown in chain dotted lines in Figure 4) the arm 29 and link are nearly at right angles and the free end of the link 36 is held within the slot 34 by the spring 36. Aerodynamic forces acting on the fin I3 are transmitted by the arm 29 to the link 30 and thence to the sides of the slot 34. The line of action of the forces on the link 30 will be against the sides of the slot 34 and will therefore not be applied to the spring 36. The tension in the spring is only applied to maintain the free end of the link 30 within the slot 34.

With the arrangement described the strength of the spring 36, since it does not require to support the fin against the aerodynamic forces acting on it, may be relatively light and this, taken in conjunction with the catch pins |9 enables one person to turn each fin in succession to its folded position.

Reference has been made above to the provision of a device for disengaging the frame I5 from the mine II when the latter strikes the surface of the water. The purpose of this is to enable the mine to sink without the fin system as it is considered undesirable that the fins should controlthe passage of the mine through the water.

The device referred to is generally indicated by the reference numeral 56 in Figures 2, 3 and 4 and will now be described with reference to these figures. The part I6 of the frame I5 carries a bracket 46 which is spaced from the right-hand flange I1 of Figure 3 and which is connected to it by a rod 4|. The bracket 46 also carries a lever 42 which is pivoted at 43. One arm of the lever 42 is constituted as a finger 43 which passes through an opening 44 in the part I6 to engage the cylindrical surface of the mine II. A spring 45 presses the finger 43 inwardly to engage the mine. The other arm 46 of the lever 42 lies be,- neath a weight 41 which is adapted to slide along the rod 4|. The weight 41 is normally held clear of the arm 46 by a locking wire 48 which passes through a hole in the rod 4|. Prior to the frame being attached to the mine II the weights 41 are raised and the locking wires 48 secured in position so that the weight is held clear of the frame 46. When the frame I5 is placed on the mine I I the finger 43 will engage the cylindrical wall and being pressed against it will hold the frame I5 in position.

It will be noted that the finger 43 does not prevent the frame I5 from being slid axially to displace the anchorage 26 for the purpose of withdrawing the pins I9 from the slots 24 side scribed above.

When the mine strikes the water the impact urges the Weight 41 to the bottom of the rod 4|. The strength of the wire 48 is selected so that it is sheared through under these conditions and the Weight 41 will descend to strike the arm 46 and withdraw the finger 43 from the mine The mine will therefore be free to slide out of the part I6 of the frame It. Two such devices BII'are' rovided at diagonany opposite corners of the frame I5 as shown in Figure 2.

It will be understood that the present invention is not limited in its application to sea mines. The collapsible fin arrangement described finds ap plication to bombs and torpedoes of large size where the fins unless collapsed would take up an excessive amount of storage room. 1

I claim:

For Pmlectile, a fin assembl' com frame having an open ended slot issrofif i ti i rality of fins having open ended slots pivotally mounted on the frame, means urging each fin from a folded position against the frame to an extended position projecting from the frame, separate catch pins having a pair of axially spaced heads, the shank of the pin being adapted to enter the open ended slots in said frame and fin so that the force urging the fin to its extended position is taken by the heads of the pin, a plurality of separately folded radiating arms, an anchorage centrally of the arms, means releasably connectin the separately folded arms to said anchorage, means connecting each arm to one of the separate catch pins, and means for simultaneously releasing the separate catch pins from all the fins and for simultaneously connecting the fins to the central anchorage by said radiating arms.

2. A fin assembly as claimed in claim 1 wherein the central anchorage of the radiating arms is adapted to be engaged by the projectile and is so arranged that when the assembly is fitted into its final position on the projectile the anchorage is moved to withdraw the pin from the open ended slot in the frame.

3. A fin assembly as claimed in claim 2 wherein there is provided for each fin a plate having an open-ended slot which extends substantially normal to the fin when the latter is in the fully extended position, a spring urging each fin to its fully extended position, the force of the spring being applied to the fin through a linkage comprising a pair of pivotally connected members of which one is substantially normal to the fin and the free end of the second is strained by said spring to travel along one side of, and enter, said slot that limits the extent of movement of the second member so that when the fin is fully extended the pair of pivotally connected members are at substantially right angles to one another and the second member is substantially normal to the length of the slot whereby the aerodynamic forces on the fin are applied through said members to the sides of the slot.

EVELYN CECIL MUSCHAMP DASSIS FONSECA.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,442,845 Kee Jan. 16, 1923 1,879,840 Brandt Sept. 27, 1932 1,890,175 Brandt Dec. 6, 1932 FOREIGN PATENTS Number Country Date 589,346 Great Britain June 18, 1947 

